The US military is built and structured to fight major wars accross the globe.
at the same time with different opponents.
It could be done but it would be a stressfull situation and piss off a whole bunch of NG and Reservist .
But you would think for it to happen it would be an emergency so they wouldnt be THAT pissed off.
But the equipment and the logistics and the manpower is in place for a cconventional war RIGHT now against a MAJOR opponent...like China or the Former Soviets..and the doctrine and the plans are ready...thats what a PROFFESional military does wwhen its not killing people and blowing things up..they make plans and practice how to do it .
It would take about 72 hours to put the RD force in place and about a month to fully deploy an Army against the NK...way too late for the South Koreans ...Unless they can fight .
Because the US would be blowing NK to bits and little bits with air power and carrier strikes and cruise missile strikes..if the ROKs can hold the remaining targets for a while NK is history in a month...then you figure on how China wants its government to look like ...BTW ..China may just attack them from the North if they pull any more **** .
The Chinese have no desire to become a fallout zone . And are more than a little pissed .
Is the US stretched thin with its CURRENT force deployments yes...but if you do not have an idea what CURRENT FORCE DEPLOYMENT meanss you may make the wrong assumption that the US MILITARY is stretched thin...
YOU be in for big sooooprise munchkin man El Kimillbung diablo .